1. Field of the Invention
The invention relates to a system for cleaning a wafer, and more particularly to a system effectively removing particles from a circumferential edge of a wafer.
2. Description of the Related Art
Generally, after a wafer undergoes chemical mechanical polishing (CMP), the top and bottom surfaces thereof must be cleaned. Slurry and particles are thus removed from the wafer.
In a cleaning process, a wafer is transported into a cleaning chamber and held by multiple chuck rollers. The chuck rollers rotate, driving the wafer to rotate. A top cleaning brush and a bottom cleaning brush respectively rotate and move on the top and bottom surfaces of the wafer, removing the particles therefrom. Wafers, which have been cleaned by the aforementioned process, are stacked in a wafer pod and transported to a processing machine for subsequent processing.
Accordingly, particles can be removed from the top and bottom surfaces of the wafer by the aforementioned cleaning process. Nevertheless, particles on a circumferential edge of the wafer cannot be removed by the top and bottom cleaning brushes. During transportation of the wafers, the particles on the circumferential edge of the upper wafer fall onto the top surface of wafers below, causing ill effects during subsequent processing of the wafers, thus reducing yield or reliability thereof.
Hence, there is a need for a system effectively removing particles from a circumferential edge of a wafer.